Larry the Downing Street cat has preferred hanging out in the corridors of power to stalking in the grass. Photograph: Getty Images

It's a good job his political masters don't do targets any more – otherwise Larry the cat would surely have failed.

After two months in the job, Downing Street's "chief mouser" – as cats who catch government rats are called – finally snared his first prey.

On Good Friday, Larry appeared through a window from the Downing Street garden with a mouse in his mouth. He is believed to have dropped his swag at the feet of the prime minister's secretaries.

Recruited to deal with a rodent problem – black rats have been seen bolting across the Downing Street lawn – Larry has preferred hanging out in the corridors of power to stalking in the grass.

Announcing his new hire in February, the prime minister's spokesman said Larry had been "highly recommended".

The four-year-old tabby, who came from the Battersea dogs and cats home, had a "very strong predatory drive and high chase-drive and hunting instinct", the spokesman said.

But whether he is vegetarian, pacifist or just more of a political anorak than a trained killer, No 10 staff had to resorted to training Larry by giving him a toy mouse to play with when he failed to catch any prey for two months.

During Margaret Thatcher's period as PM, a stray called Humphrey was adopted after wandering into No 10.

Humphrey was kept on by John Major, but was sacked when Tony Blair entered office in 1997, with Cherie Blair thought to have been responsible for blackballing him.